This invention relates to the creation of heat sinks for semiconductor on insulator (SOI) circuits using polysilicon pillars.
Recent improvements in bonded wafer semiconductor on insulator (SOI) technology makes it feasible to use SOI material in lower cost applications. See, for example, Laura Peters, SOI Takes Over Where Silicon Leaves Off, Semiconductor International, March 1993, pp. 48-51; or, H. H. Hosack, Recent Progress in SOI Materials For the Next Generation of IC Technology, The Electrochemical Society Interface, Spring 1993, pp. 51-57. Bonded wafers for SOI processes are available, for example, from Hughes Danbury Optical Systems, Inc. Precision Materials Operations, having a business address of 100 Wooster Heights Road, Danbury, Conn. 06810-7589.
SOI material offers performance advantages over bulk complementary metal on silicon (CMOS) technology due to lower parasitic capacitances. However, the isolation feature which improves performance also has disadvantages. The oxide isolation effectively insulates the transistors, reducing the heat dissipation. This can reduce the performance and reliability of high current components such as input/output (I/O) drivers and clock drivers.